1. Field of the Invention
The invention relates to aircraft gas turbine engine turbine cooling systems and, particularly, to rotating annular cavities that accumulate debris from such systems.
2. Description of Related Art
Gas turbine engines typically include a core engine having in serial, axial flow relationship, a high pressure compressor to compress the airflow entering the core engine, a combustor in which a mixture of fuel and the compressed air is burned to generate a hot gas flow. A high pressure turbine is rotated by the hot gas flow and drives the high pressure compressor through an interconnecting high pressure shaft. A low pressure turbine aft of the high pressure turbine drives a fan forward of the high pressure compressor by a low pressure shaft. Various cooling systems are used to duct relatively cool compressor air to the turbine for cooling purposes. The cooling air for turbine cooling contains a small amount of dust and debris which can accumulate in various annular cavities in the turbine as well as other rotating parts of the engine. As an example, cooling air may be flowed though holes in a shaft of a turbine disk and accumulate in an adjacent annular cavity in a hub of the disk. Such an arrangement may be found in a high pressure turbine of a General Electric CF6-80 series engine.
Such cavities are closed at an outer diameter and open at an inner diameter of the hub. Dust and debris can become entrapped and build up over time with continued operation of the engine. Since the rotor internal airflow usually has both axial and circumferential velocity relative to the rotor, such debris can circumferentially scrub the rotating part internal surfaces and, over time, cause damage to the parts.
It is highly desirable to have an apparatus that can prevent debris from circumferentially scrubbing internal surfaces of rotating part cavities that are closed at an outer diameter and open at an inner diameter of the parts and which over time can cause damage to the parts.